IconThemeData of(BuildContext context)

The data from the closest instance of this class that encloses the given context.

Defaults to the current ThemeData.iconTheme.

Typical usage is as follows:

IconThemeData theme = IconTheme.of(context);

Source 

static IconThemeData of(BuildContext context) {
  IconTheme result = context.inheritFromWidgetOfExactType(IconTheme);
  return result?.data ?? Theme.of(context).iconTheme;
}